Tissue temperature is critical to cellular bioenergetics and can be useful clinically to locate blood perfused regions in diseased or inflamed tissue. Clinical use of tissue temperature or thermography has been limited by uncertainties in temperature measurement. The most common method for temperature measurement is to use invasive micro-electrodes or thermocouples. However, these probes have several disadvantages, including: tissue damage, alterations of tissue temperature and single point detection. Measurement of tissue temperature using emitted light in the infrared or microwave region has overcome many of the disadvantages of electrode measurements. Assuming the tissue is a blackbody radiator, noninvasive images of tissue are possible using infrared emission. However, the extremely high extinction coefficients for the infrared wavelengths in wet tissue result in light penetration of a few hundred microns or less. For wet tissue such as the lung or gut, this penetration depth is not sufficient. Likewise, infrared light is not easily coupled into fiber optic systems for endoscopic or bronchoscopic measurements.
U.S. Pat. No. 5,262,644, J. F. Maguire describes a method and apparatus for providing spectroscopic information remotely using incident radiation, a detector and fiber optic coupling; it is indicated that the temperature of a sample may be deduced from the intensity difference between the Stokes and anti-Stokes lines by application of the Boltzmann relationship to the intensity difference.